Thumbdata on Android: what is this file, why is it huge and how to delete it without risk

Have you ever looked into the memory of your Android smartphone and discovered a mysterious file there thumbdatathat takes up gigabytes of space? Or have you noticed that after cleaning the gallery a year later, the memory is again “clogged” with unknown things? This file is one of the most common “eaters” of internal storage, but few people understand why you need it and whether it is possible to get rid of it.

In this article we will figure out what it is thumbdatawhy it appears even on new devices, how to find it in the file system and - most importantly - whether this file can be deleted without consequences for the operation of the phone. You will also learn how to prevent it from growing in the future and what alternative solutions will help save space on Android.

Spoiler: deleting thumbdata is possible, but it will not always bring the expected effect. And in some cases, cleaning can even slow down the gallery. Let's take a closer look.

What is thumbdata and why do you need it on Android?

File thumbdata (the full name is usually thumbdata3--xxxxxxxx.db or thumbdata4--xxxxxxxx.db) is a database of thumbnails (previews) for media files on your device. It is created automatically by the Android system or application Gallery (depending on the OS and firmware version) to speed up the display of photos and videos.

Imagine: you open a gallery, and instead of downloading a full-size image each time (weighing, for example, 5-10 MB), the system shows you a smaller copy of it from the cache - weighing only 10–50 KB. This saves time, traffic (if photos are stored in the cloud) and processor resources. This is what thumbdata.

• 📌 Where it is storedis responsible for: usually in the folder /sdcard/DCIM/.thumbnails or /storage/emulated/0/DCIM/.thumbnails (on some devices the path may differ).
• 📊 Size: from several megabytes to 10+ GB on devices with a large media library.
• 🔄 Update: the file is overwritten when adding new photos/videos or after clearing the gallery cache.

On older versions of Android (before Android 10) this file was the same for all media files. In new versions of the OS, some manufacturers (for example Samsung or Xiaomi) split it into several databases to speed up access to thumbnails.

Why does thumbdata take up so much space

The main reason for file growth thumbdata — it a large number of media files on the device. The more photos and videos you store, the more thumbnails the system generates. Moreover, we are talking not only about photos in the gallery, but also about:

• 📷 Screenshots (folder Screenshots or Pictures/Screenshots).
• 🎵 Album covers from music applications (for example, Spotify or YouTube Music).
• 📥 Images from instant messengers (WhatsApp, Telegram), if they are saved to the phone memory.
• 🖼️ Pictures from downloaded documents (PDF, Word) or archives.

Second reason — duplication of thumbnails. Sometimes Android creates multiple copies of the same preview for different screen resolutions or applications. For example, one thumbnail can be stored for display in the gallery, another for a widget on the main screen, a third for quick viewing in the file manager.

The third, less obvious reason is errors in the gallery. If the application crashes while generating thumbnails, the file thumbdata may become bloated due to incorrectly written data. In such cases, its size may exceed 20–30 GB, although there are much fewer actual media files on the device.

⚠️ Attention: On some devices (especially with custom firmware) the file thumbdata can store thumbnails not only for the gallery, but also for system applications, for example Contact (for profile photos) or Phone (for call covers). Deleting such a file will lead to the disappearance of previews in these applications.

Is it possible to delete thumbdata without consequences

Short answer: yes, you can delete it, but with reservations. The file thumbdata is a cache, not critical system data. After deleting it:

• ✅ The gallery will work, but the first time you open it after cleaning it will begin re-generating thumbnailswhich can take from a few minutes to an hour (depending on the number of media files).
• ✅ This will free up space on your internal storage (sometimes up to 5–10 GB).
• ⚠️ Some widgets (for example, the gallery widget on the main screen) may temporarily display empty previews.
• ❌ No other problems (crashes, data loss, errors in Android operation) will not occur.

However, there are nuances:

1. On Android 11+ some manufacturers (for example, Samsung) use protected thumbnail databases, which are restored automatically even after manual deletion. In this case, cleaning will not have a long-term effect.
2. If you use third-party galleries (for example, Google Photos, QuickPic), they can create their own thumbnail cache in another folder.
3. On devices with small amount of RAM (1–2 GB), re-generation of thumbnails after deletion thumbdata may cause lags.

How to find and delete thumbdata manually

To delete a file thumbdatayou will need file manager with access to hidden folders (for example, Solid Explorer, FX File Explorer or standard Explorer on Xiaomi/Redmi). Follow the instructions:

1. Open the file manager and turn on display hidden files (in the settings or through the menu).
2. Go to the path:

   /storage/emulated/0/DCIM/.thumbnails

   If there are no folders .thumbnails check:

   /sdcard/DCIM/.thumbnails

   or (on some devices):

   /storage/self/primary/DCIM/.thumbnails

3. Find files with names thumbdata3--.db, thumbdata4--.db or simply thumbnails.db.
4. Delete them (you can select everything and click “Delete”).
5. Empty Trash (if the file manager uses it).
6. Reboot the device (optional, but recommended to free up the cache).

If you If you use Windows and connect the phone as a USB drive, hidden folders (starting with a dot) may not be displayed. To see them:

1. In Windows Explorer go to the tab View.
2. Tick the box Hidden elements.
3. Then in Folder options uncheck Hide protected system files.

Enable display of hidden files

Back up important media files

Close all applications that use the gallery

Check free space after deletion-->

Automatic cleanup of thumbdata: apps and settings

If you don't want to manually To dig into the file system, you can use Specialized applications or the built-in Android tools. Here are the most effective methods:

adb shell rm -rf /sdcard/DCIM/.thumbnails/*

For users Samsung there is an additional way: in the application My file (My Files) go to Storage analysis → Unneeded data and select Clear thumbnails. This method removes thumbdata without the risk of damaging other files.

⚠️ Attention: Some "cleaners" (for example, Clean Master or CCleaner) promise to delete thumbdata, but in practice they often delete only part of the files or leave empty folders. It is better to use proven tools like SD Maid.

What to do if thumbdata appears again

Deleting thumbdata is a temporary solution. After some time, the file will reappear and its size will grow as more media is added. To prevent its growthfollow these tips:

• 🔄 Disable automatic generation of thumbnails (if your firmware allows it). For example, in MIUI on Xiaomi you can disable pre-loading in the gallery settings.
• 🗑️ Clear the gallery cache regularly (once every 1-2 months) through the app settings.
• ☁️ Use cloud galleries (for example, Google Photos), which store thumbnails on the server, not on the device.
• 📁 Move media files to an SD card (if supported). Thumbnails for files on a memory card are often stored separately and take up less space.
• 🚫 Limit saving media from messengers. In WhatsApp i Telegram you can disable autosaving of photos/videos to the gallery.

If you often work with a large number of images (for example, a photographer or designer), consider this option use Professional file managers like FX File Explorer or Mixplorer. They allow you to:

• Disable the generation of thumbnails for specific folders.
• Customize the cache size.
• Use external storage to store previews.

Frequent errors when working with thumbdata

Many users make mistakes when trying to clear thumbdatawhich leads to the opposite effect - the file grows even larger or the gallery malfunctions. Here are the most common mistakes:

• 🔹 Deleting a folder .thumbnails without emptying the trash. The files remain in the trash and continue to take up space.
• 🔹 Using “cleaners” with aggressive algorithms. Some apps (for example, Avast Cleanup) delete not only the cache, but also the media files themselves.
• 🔹 Deleting thumbdata via Root Explorer without superuser rights. This may cause the gallery to crash.
• 🔹 Clearing the system application cache (for example, Media storage), which leads to the regeneration of all thumbnails from scratch.
• 🔹 Ignoring backup. If after deleting thumbdata the gallery starts to lag, you may need to reset the application settings, which will delete albums and tags.

Another common mistake is deleting thumbdata on devices s adoptable storage (when the SD card is used as internal memory). In this case, the file may be stored on the card, and deleting it without unmounting the drive will lead to read errors.

⚠️ Attention: On some devices (for example, Huawei c EMUI) the file thumbdata can be associated with a system application Huawei Gallery. Removing it without disabling the application will lead to constant regeneration of the cache. In this case, it is better to use the built-in cleaning function in the gallery settings.